Portable motor-aspirated psychrometer



Feb. 14, 1967 J, KAHL PORTABLE MOTOR-ASPIRATED PSYCHROMETER 3 Sheets-Shea#l l Filed May 9, 1963 INVENTOR.

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Feb. 14, 1967 J, KAHL PORTABLE MOTOR-ASPIRAT ED PSYCHROMETER 5 Sheets-Sheet 2 Filed May 9, 1963 his Harney Feb i4, 1957 J, KAHL PORTABLE MOTOR-ASPIRATED PSYCHROMETER 5 Sheets$heet s Filed May 9, 1963 seph Hah! BY MCMS/ 5, Swim,

United States Patent O 3,303,700 PORTABLE MGTOR-ASPIRATED PSYCHROMETER Joseph Kahl, 14 Horatio St., New York, N.Y. 10024 Filed May 9, 1963, Ser. No. 279,177 2 Claims. (Cl. 73-338.6)

The present invention reltes to a psychrometer. More particularly, the invention relates to a portable motoraspirated psychrometer.

The wet and dry bulb thermometer, or psychrometer, measures relative humidity. Two exactly similar thermometers are mounted side by side. The bulb of one thermometer is wrapped in a wick which is Wet. The wick covered bulb is cooled by evaporation. The rate of evaporation, and hence the resultant cooling, depends in a definite manner upon the relative humidity of the air. A table indicates the humidity in terms of the actual air temperature as indicated lby the dry bulb thermometer, and the difference in temperature between the web bulb and the dry bulb.

The principal object of the present invention is to provide a new and improved psychrometer.

An object of the present invention is to provide a new and improved portable motor-'aspirated psychrometer` An object of the persent invention is to provide a psychrometer which functions with accuracy and reliability. v

An object of the present invention is `to provide a psychrometer of sturdy and rugged construction.

An object of the present invention is to provide a psychrometer which may be readily assembled and disassembled.

Another object of the present invention is to provide f a portable motor-aspirated psychrometer which is readily operable as a manually-aspirated psychrometer.

In order that the present invention may be readily carried into effect, it will now be defined with reference to the accompanying drawings, wherein:

FIG. l is a perspective view of an embodiment of the psychrometer of the present invention showing the housing, the thermometer frame and the air duct member separated from each other;

FIG. 2 is a side View of the embodiment of the psychrometer of FIG. l of the persent invention showing half the housing, the thermometer frame and the air duct member;

FIG. 3 is 4a top View of the thermometer frame and a partly cut away top View of the air duct member of the embodiment of FIG. 1;

FIG. 4 is a top View of the air duct member of the embodiment of FIG. l;

FIG. 5 is a front view of the air duct member of FIG. l;

FIG. 6 is a bottom view of the air duct member of FIG. l;

FIG. 7 is a side view of the air duct member of FIG. 1;

FIG. 8 is a back view of the air duct member of FIG. 1;

FIG. 9 is a perspective view of the spring contact of FIG. l;

FIG. 10 is a side view of a portion of the embodiment of FIG. 1, showing a suitable position of the spring contact of FIG. l and FIG. l1 is a circuit diagram of an electrical system for the psychrometer embodiment of FIG. l.

In the figures, the same components are identified by the same reference numerals.

In a manually-aspirated psychrometer, the thermometer frame of FIGS. l, 2 and 3 is swung through the air at the end of la cord held by the observer in order to provide a suitable fiow of air past the bulbs of the wet and ICC dry bulb thermometers. In a motor-aspirated psychrometer, a motor-blower arrangement provides a suitable flow of air past the thermometer bulbs. In a portable motoraspirated psychrometer, a battery-powered electric motorblower arrangement provides a suitab-le flow of air past the thermometer bulbs.

The three basic structural parts of the psychrometer of the present invention are the housing 11, the thermometer frame 12 and the air duct member 13. The basic components of the housing 11 are the motor-blower arrangement comprising a motor 14 and a fan 15, a power source for the motor-blower arrangement comprising a battery or a number of batteries of which three batteries 16 are shown in FIG. 2, a control arrangement shown in FIG. l1, and an air duct 17.

The basic function of the thermometer frame 12 is to support the wet and dry bulb thermometers in a manner wherein they may yboth be readily observed and wherein the bulb of the wet bulb thermometer may be made wet without effecting the dry bulb of the dry bulb thermometer. The basic function of the .air duct member 13 is to cooperate with the air duct 17 of the housing 11 and with the bulbs of the wet and dry bulb thermometers to provide a suitab-le flow of air past said bulbs.

The housing 11, as shown in FIGS. 1 and 2, has a longitudinal dimension 18 which is the same as 4the longitudinal dimension of the thermometer frame 12 and the air duct member 13 combined. The width dimension of the` housing, which is the same as the width dimension 19 of the thermometer frame 12, extends perpendicularly to the plane of the sheet of drawing of each of FIGS. 2 and 3, as shown in FIG. 1. The housing 11 has a first lateral dimension 21 extending substantially perpendicular to the longitudinal dimension 18 in the plane of the sheet of the drawing of FIG. 2 and a second lateral dimension 22 extending substantially perpendicular to the longitudinal dimension 18 in the plane of the sheet of the drawing of FIG. 2 and susbtantially parallel to the first lateral dimension 21. The first lateral dimension 21 is of greater magnitude than the second lateral dimension 22 so that a step 23 is formed in the top of the housing 11.

The step 23 serves to properly position the thermometer frame 12 on the top surface 24 of the housing 11 with the end surface 25 of said the thermometer frame in contact with the surface of the frame positioning step 23 and with the bottom surface 26 in contact with said top surface of said housing.

The housing 11 is preferably formed by two similar halves, as indicated by the division line 27 of FIG. 1. FIG. 2 shows half the housing 11. A longitudinal divider or rib 28 extends substantially perpendicularly from the inside surface of each half of the housing 11 and is preferably integrally molded with the corresponding half housing. The longitudinal divider 28 divides the half housing into two longitudinal compartments or cavities. A lateral divider or rib 29extends Isubstantially laterally from the bottom surface 31 of the half housing at the air duct end of the housing. Other lateral ribs or dividers such as, for example, the ribs 32, 33 and 34, may be provided to strengthen the structure of the housing 11 or to form desired compartments. The longitudinal divider 28 is substantially perpendicular the side surfaces and end surface 25 and is substantially parallel to the top and bottom surfaces 24 and 31. The lateral divider extends inside said housing substantially perpendicular to the side surfaces and top and bottom surfaces 24 and 31 and is substantially parallel to the end surface 25.

The air duct 17 is formed in the housing 11 in substantially cylindrical configuration, a half cylinder being formed in each half housing. The air duct 17 opens in the upper part 35 formed by the step 25 in the top surface 24 of the housing 11 in a substantially circular air duct aperture 36. The air duct 17 extends from theupper part 35 of the top surface 24 of the housing 11 to a motor compartment or cavity 37 formed by the end surface 38 of said housing and the lateral divider 29. The air duct 17 opens into the top 39 of the motor compartment 38.

The motor compartment 37 opens in the bottom surface 31 of the housing 11 in a motor plate aperture 41 and opens in the side surfaces 42 and 43 of said housing in windows 44 and 45, respectively. The motor compartment 37 opens into the bottom longitudinal 4compartment of the housing 11 through a passage 46 between the longitudinal divider 28 and the end of the lateral divider 29 and opens into the top longitudinal compartment of said housing through a wire aperture 47 formed in the later-al divider 32.

A lamp aperture 48 is formed through the top surface 24 of the housing 11 and an auxiliary aperture 49 is formed through said top surface of said housing in spaced relation from the lamp aperture. The end of the housing 11 opposite the end surface 38 thereof is open and has a pair of parallel lips 51 formed around the top and both sides of its edge forming a closure groove 52 therebetween. A plate (not shown) is adapted to be slidably positioned in the closure groove 52-and may be inserted in said closure groove through the bottom edge to close the end of the housing 11 and may be removed through said bottom edge to open the end of said housing to permit access to said housing.

The upper part 35 of the top surface24 has a lip 53 formed around three sides of a rectangular area surrounding the air duct aperture 36 forming a duct groove 54 around the air duct aperture 36 except for the edge on the end surface 38 of the housing 11. The air duct member 13 is adapted to be slidably positioned in the duct groove 54. The bottom surface 31 of the housing 11 has a pair of parallel lips 55 formed around the motor plate aperture 41 forming a motor groove A56 therebetween. The motor 14 is adapted to be positioned in the motor groove 56. l

The motor 14 is mounted on a motor plate (not shown) which is positioned in the motor groove 56 before the two half housings are joined together. The motor 14 drives a fan 57 which has a diameter slightly larger than the diameter' of the air duct 17. Themotor 14 and the motor-driven'fan 57 are positioned and dirnensioned so that the fan 57 is directly below the air duct 17 and coaxially aligned therewith.

Batteries 16 for driving the motor 14 are placed in the bottomilongitudinal compartment of the housing 11 and may bereadily inserted and removed through the closure area defined by theV closure groove 52.V A light bulb or lamp 58 is mounted on a'lamp support 59 mounted on the housing 11 and extending through the lamp aperture 48. The batteries 16 provide electrical energy for the motor 14 and for the-lamp 58 through a spring contact 61.

The spring contact'61 is shown in detail in FIG. 9. The spring contact 61 comprises two strip-like sheets of conductive material -such as, for example, copper and a sheet of insulating material such as, for example, insulating plastic tape. The two sheets of conductive material Vare positioned in side by sideV relation by the insulating material 62. A sheet 63 of electrically conductive material is shaped in substantially S coniigurationrwith the insulating material 62. The sheet 63 is thus formed with a topportion 64, a stem portion 65 and a bottom portion formed by the insulating material 62. The other sheet 66 ofelectrically conductive material is shaped in substantially U conguration with the electrically insulating material 62. The sheet 66 is thus formed with a iirst leg portion 67 comprising the insulating material 62 and a part 68 of conductive material bent at an obtuse angle with the insulating material, a second leg portion 69 comprising three parts 71, 72 and 73 bent at obtuse angles with each other and a head portion 74 joining the first and second legportions.

The conductive sheets 63 and 66 of the spring Contact 61 are resilient and maintain contact between the batteries 16 and the motor contacts 75 of ywhich only one is shown in the figures). The spring contact 61 is positioned in the housing 11 in the manner shown in FIG. 10 with the lateral divider V29 in the area formed by the first and second leg portions 67 and 69 -of the conductive sheet 66 and with the head portion 74 of the conductive sheet 66 in the passage 46. The lateral divider 29 prevents the spring contact 61 from shifting in the longitudinal direction and the longitudinal divider 28 prevents said spring contact from shifting in the lateral direction. Thus, due to its resiliency and its position with the lateral and longitudinal Vdividers 29 and 28, respectively, the spring contact 61 maintains electrical contact between the batteries V16 and the motor 14.

The spring contact 61 maintains direct electrical contact between the batteries 16 and the motor 14 without the need for soldered'connections. The lateral divider 29 so positions the spring contact 61 that if the batteries 16 shift longitudinally and exert pressure on said spring contact the Vsaid spring contact maintains electrical Contact with the motor contacts 75. The motor contacts 75 are spaced from each other. One motor contact 75 contacts the conductive sheet 63 and the other motor contact 75 contacts the conductive sheet 66. Since the conductive sheets 63 and 66 of the spring contact 61 are insulated from each.

other by the insulator 62, the motor 14 is suitably placed in circuit with the lamp 58 and the battery 16. One motor contact makes electrical contact With the stem portion 65 of the sheet 63 and the other motor contact makes electrical contact with the part 68 of the sheet 66. The second leg portion 69 -of the conductive sheet 66 maintains electrical contact with the batteries 16.

A hole 76 is formed through the top portion 64 of the sheet 63 and a hole 77 is formed through the head portion 74 of the sheetV 66. A potentiometer or rheostat 78 is mounted in an aperture (not shown) formed through a half housing. The potentiometer 78 is electrically connected between the `batteries 16 and the lamp v58 by an electrical conductor 79 soldered to the conductive sheet 66 of the spring contact 61 at the hole 77, an electrical conductor81 between the potentiometer and the lamp 58,

a conductor 82 between the lamp and the potentiometer,

and a conductor 83 between the potentiometer and the 66 of the spring contact 61 and is electrically connected to the potentiometer 78 by a conductor 85 soldered to the conductivel sheet 6.3 of the spring contact 61 at the hole 76.

The potentiometer 78 is manually operated, preferably through a knob or dial in readily accessible position outside the housing 11 at the potentiometer aperture (not shown). The potentiometer 78 functions first as anON- OFF switch, diagrammatically illustrated as a switch 86 in FIG. 11, so that when the arm 87 of said potentiometer 1s -turned from its inactive position it first closes the circuit vla its switch portion 86 to energize the motor 14. As the potentiometer arm 87 is turned it moves in the direction of arrow 88 to gradually cut the potentiometer resistance out of the circuit from the OFF position wherein the entire resistance of the potentiometer is in circuit So that the lamp 58 is OFF to the FULL ON position where- 1n there is no resistance of the potentiometer in circuit so Athat the lamp is FULL ON at its maximum brightness. Thus, as the knob of the potentiometer 78 is turned from its OFF position to its FULL ON position, the motor 14 is energized and drives the fan 57 and the lamp 58 gradually lights from a dim light to its maximum brightness. If the potentiometer 78 is merely turned ON from its OFF position, the motor is energized, but the lamp 58 does not begin to light unless the knob of the potentiometer is moved still further. Thus, the motor may be energized without the lamp 58 for daytime use or with the lamp energized also, for nighttime use.

The conductors 79 and 85 pass through the wire aperture 47 in the lateral divider 32 so that these conductors are not caught between the half housings when the half housings are aiixed to each other to form the housing 11. The half housings are preferably joined by screws (not shown). The lamp aperture 48 enables the lamp 58 to be positioned in the longitudinal direction so that it provides a maximum of light by which to read the thermometers of the thermometer frame 12. The auxiliary aperture 49 enables a second lamp (not shown) to be utilized, if desired.

The thermometer frame 12 is adapted to be positioned on the top surface 24 of the housing 11 between the step 23 and the open end portion of said housing bounded by the closure lips 51. The thermometer frame 12 is preferably made of translucent plastic material with an opaque coating on the outside surfaces. A lamp compartment or recess or cavity 89 is formed in the bottom Surface 26 of the thermometer frame 12. The thermometer frame 12 is normally mounted on the housing 11 with the bottom surface 26 thereof on the top surface 24 of the housing, with the end surface 25 thereof contacting the stop surface 23 and with the end surface 91 coplanarly positioned with the outer closure lips 51 of the housing. In this position of the thermometer frame 12, the lamp 58 is positioned in the lamp compartment S9. The thermometer frame 12 is preferably affixed to the housing 11 by screws.

The thermometer frame 12 has two grooves 92 and 93 formed in the top surface 107 thereof extending longitudinally in substantially parallel relationship. The grooves 92 and 93 seat the thermometers which provide the indicating portion of the psychrometer. A wet bulb thermometer 94 is seated in one of the grooves 92 and 93 such as, for example, the groove 92. A dry bulb thermometer 95 is seated in the other groove 93. The stems of the wet and dry bulb thermometers 94 and 95, respectively, are seated in the grooves 92 and 93 with their bulbs 96 and 97, respectively, extending beyond the thermometer frame 12 and spaced a predetermined distance beyond the end surface 25 thereof. This predetermined distance is such that when the thermometer frame 12 is positioned on the housing 11, the bulbs 96 and 97 are directly over the air duct aperture 36 of said housing.

The translucent material such as, for example, acrylic plastic, of the thermometer frame 12 enables the lamp 58 i to illuminate the thermometers and enables the thermometers to be read in the dark. The thermometer frame may be cast or machined with grooves (not shown) formed in its bottom surface 26 to accommodate conductors from the potentiometer to the lamp.

The thermometers 94 and 95 are secured in position in the grooves 92 and 93 by clips 98 and 99 affixed to the thermometer frame. Each of the thermometers 94 and 95 has two spaced tubular cushioning sleeves 101 and 102 and 103 and 104 around it and the clips 98 and 99 press on these sleeves to hold the thermometers in place. Thus, the thermometei clip 98 press-es on the sleeve 101 around the thermometer 94 and the sleeve 103 around the thermometer 95 and the thermometer clip 99 presses on the sleeve 102 around the thermometer 94 and the sleeve 104 around the thermometer 95.

The thermometer clip 99 has two apertures 105 and 106, respectively, formed therethrough. A pip or nib formed on and projecting from the stem of the thermometer 94 is adapted to iit into, and thus be held in position by, the aperture 105 of the thermometer clip 99 and a pip or nib formed on and projecting from the stem of the thermometer 95 is adapted to t into, and thus be held in position by, the aperture 106 of said thermometer clip. The thermometer clip 99 thus secures the thermometers 94 and 95 against slippage and rolling and maintains said thermometers in position with their scales in readily readable position.

Each of the side surfacesv of the thermometer fra-me 12, 108 and 109 has a spring clip recess formed in it adjacent the end surface 25. Spring clip recess 110 Iis formed in the side surface 108 and spring clip recess 111 is formed in the side surface 109. Each of the spring clip recesses 110 and 111 is adapted to accommodate an air duct member spring clip 112 and 113, respectively. Each air duct member spring clip 112 and 113 extends in the longitudinal direction of the thermometer frame 12 beyond the end surface 25 thereof and substantially parallel to the side surfaces of said thermometer frame. Each air duct member spring clip 112 and 113 is a strip of resilient metal or other suitable material having waves or undulations 114 and 115, respectively, formed in the portion thereof extendv ing beyond the end surface 25. The air duct member spring clip 112 is suitably affixed to the thermometer frame 12 in the spring clip recess 110. The spring clip recess 110 maintains the air duct member spring clip 112 in position. The air duct member spring clip 113 is suitably affixed to the thermometer frame 12 in the spring clip recess 111. The spring clip recess 111 maintains the air duct member spring clip 113 in position.

The thermometer frame 12 has a rod recess, groove or notch 116 -formed therein at the corner of the top surface 107 and the end surface 91 substantially equidistantly between the side surfaces 108 and 109. A laterally extending rod or pin 117 is supported in the thermometer frame 12 in parallel 4with the end surface 91 an-d the top and -bottom surfaces 107 and 26 and perpendicular to the side surfaces 180 and 109. The rod or pin 117 passes through the opening in the thermometer frame 12 made by the rod recess 116.

When the psychrometer is assembled in operating condition with the thermometer frame 12 axed, for example by two screws such as screws 11S and 119, to the housing 11 as aforedescribed, if the motor or other component Ifails to operate satisfactorily and causes a failure of the suitable air ow past the bulbs of the thermometers, a manually operable instrument may be made of the psychrometer. This is accomplished by removing the thermometer frame 12 from the housing 11 and manually whirling or slinging the thermometer frame through the air by means of a cord, rope, strap or string or wire suitably tie-d at one end -around the rod 117 and held in the hand of the operator at the other end. A small piece of wire or string 121 may be looped around the rod 117 and aixed to itself to form an endless loop to facilitate aflixing a cord or wire to the thermometer frame 12.

The air duct member 13 is shown in FIGS. 1 through 8. The air duct member 13 has a top surface 122, an end surface 123, an open end 124, a bottom surface 125, a side surface 126 and a side surface 127. The top and bottom surfaces 122 and 125 are substantially parallel to each other. The side surfaces 126 and 127 are substantially perpendicular to the top and bottom surfaces 122 and 125. The end surface 123 is substantially perpendicular to the top and bottom surfaces 122 and 125 and the open end 124 is spaced from and opposite said end surf-ace. Each of the side surfaces 126 and 127 is of Substantially planar configuration and extends betwen the top and bottom surfaces 122 and 125. The end surface 123 is of smaller dimension than the open end 124 and the side surfaces 126 and 127 thus form a taper from the end surface 123 outward to the open end 124. The air duct member 13 is a housing having an open end 1.24. A longitudinal divider 128 extends substantially perpendicular to the top and bottom surfaces 122 and 125 equi-distantly from the side surfaces 126 and 127. The longitudinal divider 128 serves to divide the air duct member 13 into two compartments, one for each thermometer 94 and 95, respectively.

A lip 129 extends from the side surface 126 coplanarly with the bottom surface and a lip 131 extends fro-rn the side surface 127 coplanarly with said bottom surface. The air duct member 13 is adapted to be positioned with its bottom surface 125 over the air duct aperture 36 of the housing 11, with the open end 124 substantially coplanar with the end surface 38 of the housing and with the end surface 123 of the air duct member contacting the end surface 25 of the thermometer frame 12. The air duct member 13 is positioned in this manner by being positioned with the lips 129 and 131 in the duct grooves 54.

A rib 132 is formed in and extends from the side surface 126 in proximity with the end surface 123 and extends substantially parallel to said end surface and substantially perpendicular to the top and bottom surfaces 122 and 125. A rib 133 is formed in and exten-ds from the side surface 127 in proximity with the end surface 123 and extends substantiallyrparallel to said end surface and substantially perpendicular to the top and bottom surfaces 122 land 125. When the air duct member 13 is positioned on the housing 11 so that its end surface 123 is in contact with the end surface 25 of the thermometer frame 12 and it is secured in the duct groove 54, the wave portion 114 of the air duct spring clip 112 of the thermometer frame v12 clamps the rib 132 of the air duct member and prevents undesired longitudinal movement of said air duct member in cooperation with the wave portion 115 of the air duct spring clip 113 of the thermometer frame, which clamps the rib 133 ofthe air duct member. Y

The end surface 123 has spaced apertures 134 and 135, respectively formed therethrough. The yaperture 134 accommodates the wet bulb thermometer 94 which extends through it so that the bulb 96 of said thermometer is positioned in the air duct member 13 in one of the compartments formed by the longitudinal divider 128 when the air duct member is in position on the housing 11. The aperture 135 accommodates the dry bulb thermometer 95 wlhich extends through it so that the bulb '97 of said thermometer is positioned in the airduct member 13 in the other of the compartments formed by the longitudinal divider 128 when the air duct member is in position on the housing 11. The vapertures 134 and 135 are spaced as yfar from the longitudinal divider 128- as possible to insure maxiirnumseparation between the wet and dryV bulbs 96 and 97.

An air duct member aperture 136 is formed 'throughV the bottom surface 125 of the air duct member 13. The longitudinal divider 128 divides the air duct member aperture 136 into a wet lbulb aperture 137 and a dry bulb aperture 133. Each of the wet and dry bulb apertures 137 and 138 is bounded by the longitudinal divider 128 and the corresponding side surfaces 126 and 127, respectively, and extends for most of the longitudinal distance between the open end 124 and the end surface 123.

When the housing 11, thermometer frame 12 and air duct member 13 are positioned in operative contact with each other, with the end surface 123 of the air duct member abutting the end surface 25 of the thermo-meter frame, with the open end 124 of the air duct member substantially coplanar with the end surface 38 of the housing,

with the end surface 91 of the thermometer frame substantially coplanar with the end surface rlips 51 of the housing, with the air duct member aperture 136 of the air duct member substantially coaxially positioned with the air duct 17 of the housing, with the lip 131 of the air `duct member in the duct groove 54 of the housing, with the lamp 58 of the housing in the lamp compartment 89 'of the thermometer frame and with the bottom surface 26V of the thermometer frame abutting the top surface 24 of the housing, the psychrometer isrready for motor-aspirated operation. The wet and dry bulbs 96 and 97 of the wet and dry :bulb thermometers 94 and 95, respectively, are then positioned in the air duct member 13 in the compartments formed by the longitudinal divider 128 thereof and over the air duct aperture 36 of the housing 11. i

The open end 124 of the air duct member 13 shouldV be pointed away from the body, in operation, and operation should not occur in the sun or under bright lights if avoidable. VThe operator should not stand near a building, vent or structure which radiates heat or cold since these affect the temperature of the air drawn into the air duct member 13 and cause incorrect temperature readings. Air measurements should be obtained in areas which represent normal atmospheric conditions in that location. The psychrometer should remain in the test area for at least five minutes before the operation to permit the thermometers to stabilize near the operating temperature before operation.

About thirty seconds Ibefore the test, the air duct member 13 should be removed and the wick covering the wet bulb 96 of the wet bulb thermometer 94 should be thoroughly wetted, but not oversaturated, with water. The water should be distilled and may be stored in a bottle which may be kept in a compartment of the Vhousing 11, such as the compartment of the :battery contact 84, which is readily accessible through the opening formed bythe lips 51. The air duct member 13 should then be replaced imposition and the motorJblower arrangement energined. When the potentiometer knob is turned from its OFF position, the motor is energized and drives the fan 57. The fan 57 creates a large draft which draws the air through the open end 124 of the air rduct member 13 over the wet and dry bulbs 96 and 97, through the air duct aperture 36 of the housing 11, through the air duct 17 of the housing and Vout through the windows 44 and 45 of said housing. p

The motor should be permitted to operate for about 50 to 60 seconds until the thermometers 94 and 95 remain fixed in their indications. The percent relative humidity may then be readily obtained from the temperature readings of the -wet and dry bulb thermometers 94 and 95 in aV manner well known in the art. Lf another liquid isused in the thermometers instead of mercury, the thermometer stabilization period is longer so that the motor should be operated for about 90 to 120r seconds. If the psychrometer is operated under circumstances which make it difficult to'read the thermometers, the potentiometer knoib should ybe turned further after the motor is energized so that the lamp 58 will illuminate the thermometers to the extent desired; the potentiometer knob being turned to its FULL ON position for maximum` illumination of the thermometers.

If the forced draft system of the psychrometer fails for some reason such as, for example, ybattery `failure or motor failure, the thermometer frame 12 may Ibe removed from the housing 11 and from the air duct member 13 and may be utilized as a manually-aspirated psychrometer. This is accomplished by the operators swinging or whirling the thermometer yframe 12 as a sling psych'rometer by means of a wire or cord held at one endin the operators hand and tied at the other end to the rod 117.

The fan blade 57 may be affixed to the motor shaft by means of a press-tit hub which is turned over or crimped over the central portion of the fan blade. The diameter of the fan blade 57 is slightly larger Vthan that of the airduct 17 of the housing 11 and results in a higher velocity air flow through said air duct than is the caseV when the Idiameter of the fan blade is smaller. The continuous long air duct 17 provides a high air tlow rate.

v The air duct member 13 is held securely in position by the lip 131, duct groove 54 arrangement and the air duct` 9 to it by the batteries as a result of battery shifting in the longitudinal direction.

While the invention has been described by means of specific examples and in a specific embodiment, we do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

What we claim is:

1. A psychrometer arrangement comprising, in combination, I

a thermometer frame having substantially parallel top and bottom surfaces, substantially parallel side surfaces substantially perpendicular to said top and bottom surfaces, and substantially parallel end surfaces substantially perpendicular to said side and to said top and bottom surfaces;

a pair of spaced grooves formed in the top surface of said frame and extending substantially parallel to the side surfaces of said frame and spaced therefrom, said grooves being open in the top surface of said frame and opening in an end surface of said frame;

a lamp compartment formed in the bottom surface of said frame opposite a portion of each of said grooves;

a wet bulb thermometer having a stem seated in one of said grooves, said stem having a nib projecting therefrom, and a bulb extending beyond said 4end surface of said frame;

a dry bulb thermometer having a stem seated in the other of said grooves, said stem having a nib projecting therefrom, and a bulb extending beyond said end surface of said frame;

ra spring clip recess formed in each side surface of said frame adjacent said end surface thereof;

a spring clip aixed to said frame in each of said spring clip recesses and extending beyond said end surface and substantially parallel to the side surfaces of said frame, each spring clip having undulations formed therein in the portion thereof extending beyond said end surface thereof;

an air duct member having substantially parallel top and bottom surfaces, side surfaces substantially perpendicular to the top and bottom surfaces of said member, an end surface substantially perpendicular to the top and bottom surfaces of said member, and an open end spaced from and opposite the end surface of said member, each of said side surfaces being of substantially planar configuration and extending between said top surface and said bottom surface;

a longitudinal divider extending substantially perpendicular to the top and bottom surfaces of said member substantially equidistantly from the side surfaces of said member, said longitudinal divider dividing said member into two substantially equal compartments;

a pair of spaced apertures formed through the end surface of said member, each opening into a corresponding one of the compartments of said member;

an aperture formed through the bottom surface of said member and opening into substantially the entire area of the compartments of said member;

a lip extending from the side surfaces of said member substantially coplanarly with the bottom surface of said member; and

a rib formed in and extending from each of the Side surfaces of said member in proximity with the end surface of said member and substantially parallel to said end surface and substantially perpendicular to the top and bottom surfaces of said member, said air duct member being adapted to be positioned adjacent said thermometer frame with the end surface of said air duct member abutting the said end surface of said frame, with the bulb of the wet bulb thermometer positioned in one compartment of said air duct member and the lbulb of the dry bulb thermometer positioned in the other compartment of said air duct member, and with the undulated portion of each of said spring clips clamping a corresponding one of the ribs of said air duct member. 2. A psychrometer arrangement comprising, in combination,

a housing having substantially parallel top and bottom surfaces, substantially parallel side surfaces substantially perpendicular to said top and bottom surfaces, and substantially parallel end surfaces substantially perpendicular to said side surfaces and to said top and bottom surfaces, one of said end surfaces being an open end;

a closure groove formed in said housing around the open end thereof;

a substantially long substantially cylindrical air duct extending into the housing from the top surface thereof and opening into said top surface;

a duct groove formed in said housing -around the opening of said air duct into the top surface of said housing;

a longitudinal divider extending inside said housing from the inside of a side surface thereof, said longitudinal divider being substantially perpendicular to the side and end surfaces of said housing and substantially parallel to the top and bottom surfaces of said housing;

a lateral divider extending inside said housing Ifrom the inside -of a side surface thereof, said lateral divider being substantially perpendicular to the side and top and bottom surfaces of said housing and substantially parallel to the end surfaces of said housing, said lateral divider forming in said housing a motor compartment opening into the bottom surface of said housing and opening into said air duct and having windows opening into the side surfaces of said housing;

a motor groove formed in said housing around the opening of said motor compartment into the bottom surface of said housing;

a motor-blower arrangement positioned in the motor compartment in said housing, said motor-blower arrangement having a motor plate, a motor mounted on said motor plate, and a fan positioned coaxially with said air duct just below the opening of said air duct into said motor compartment, said fan having a diameter slightly larger than that of said air duct, said motor plate being positioned in said motor groove;

a step formed in the top surface of said housing whereby the top surface of said step is farther from the bottom surface of said housing than is the remainder of the top surface of said housing, said air duct opening into said top surface of said step;

a thermometer frame having substantially parallel top and bottom surfaces, substantially parallel side surfaces substantially perpendicular to said top and bottom surfaces, and substantially parallel end surfaces substantially perpendicular to said side and to said top and bottom surfaces;

a pair of spaced grooves formed in the top surface of said frame and extending substantially parallel to the side surfaces of said frame and spaced therefrom, said grooves being open in the top surface of said frame and opening in an end surface of said frame;

a lamp compartment formed in the bottom surface of said frame opposite a portion of each of said grooves;

a Wet bulb thermometer having a stem seated in one of said grooves, said stem having a nib projecting therefrom, and a bulb extending beyond said end surface of said frame;

dry bulb thermometer having a stem seated in the other of said grooves, said stem having a nib projecting therefrom, and a bulb extending beyond said end surface of said frame;

a spring clip recess formed in each side surface of said frame adjacent said end surface thereof;

a spring clip affixed to said frame in each of said spring "clip recesses and extending beyond said end surface and substantially parallel to the side surfaces of said frame, each spring clip having undulations formed therein in the portion thereof extending beyond said end surface thereof, said thermometer frame being adapted to be positioned on said housing with the said end surface of said frame abutting the step of said housing and with the bottom surface of said frame abutting the top surface of said housing;

an air duct member having substantially -parallel top and bottom surfaces, side surfaces substantially perpendicular 'to the top and .bottom surfaces of said member, an end surface substantially perpendicular to the top and bottom surfaces of said member, and an open end spaced from and `opposite the end surface of said member, each of said side surfaces being of substantially planar conguration andextending between said top surface and said bottom surface;

a longitudinal divider extending' substantially perpendicular to the top and bottom surfaces of said member substantially equidistantly from the side surfaces of said member,said longitudinal divider dividing said member into two substantially equal compartments;

a pair of spaced apertures formed through the end sur- Vface of said member, each opening into a corresponding one of the compartments of said member;

an aperture formed through thebottom surface of said member and opening into substantially Ithe entire area of the compartments of said member;

a lip extending from'the side surfaces of said member substantially coplanarly with the bottom surface of .said member; and

a `Irib formed in and extending from each of the side surfaces of said memberin proximity with the end surface of said member and substantially parallel to air duct member being adapted to be positioned adjacent said thermometer frame with the end surface of said air duct member abutting the said end surface of said frame, with the bulb of the Wet bulb thermometer positioned in one compartment of said air duct member and the bulb of the dry bulb thermometer positioned in the other compartment of said air duct member, and with the undulated portion of each .of said spring clips clamping a corresponding one of the ribs of said air duct member, said air duct member being adapted to be positioned on said housing with the bottom surface of said air duct member abutting the top surface of the step of said housing and with the lip of said air duct member the duct groove of said housing.

References Cited by the Examiner UNITED STATES PATENTS 1,743,126 l/1930 Fortier 73-338.6 v 2,081,925 6/ 1937 Graf 292-76 X 2,107,077 2/1938 Magner 73-338.6 2,159,133 5/1939 Chappell et al. 73-338.6 2,342,831 2/1944 -Borchers 292-17 2,435,588 2/1948 Hintsala 73-373V 2,606,446 8/1952 Lamb et al. 73-338.6 2,728,056 12/1955 Montmollin 339-19 2,782,387 2/1957 Coleman 339-19 2,894,391 7/1959 Colt et al 73-338.6

LEONARD FORMAN, Primary Examine".

ISAAC LISANN, Examiner.

35 W. D. MARTIN, Assistant Examiner. 

1. A PSYCHROMETER ARRANGEMENT COMPRISING, IN COMBINATION, A THERMOMETER FRAME HAVING SUBSTANTIALLY PARALLEL TOP AND BOTTOM SURFACES, SUBSTANTIALLY PARALLEL SIDE SURFACES SUBSTANTIALLY PERPENDICULAR TO SAID TOP AND BOTTOM SURFACES, AND SUBSTANTIALLY PARALLEL END SURFACES SUBSTANTIALLY PERPENDICULAR TO SAID SIDE AND TO SAID TOP AND BOTTOM SURFACES; A PAIR OF SPACED GROOVES FORMED IN THE TOP SURFACE OF SAID FRAME AND EXTENDING SUBSTANTIALLY PARALLEL TO THE SIDE SURFACES OF SAID FRAME AND SPACED THEREFROM, SAID GROOVES BEING OPEN IN THE TOP SURFACE OF SAID FRAME AND OPENING IN AN END SURFACE OF SAID FRAME; A LAMP COMPARTMENT FORMED IN THE BOTTOM SURFACE OF SAID FRAME OPPOSITE A PORTION OF EACH OF SAID GROOVES; A WET BULB THERMOMETER HAVING A STEM SEATED IN ONE OF SAID GROOVES, SAID STEM HAVING A NIB PROJECTING THEREFROM, AND A BULB EXTENDING BEYOND SAID END SURFACE OF SAID FRAME; A DRY BULB THERMOMETER HAVING A STEM SEATED IN THE OTHER OF SAID GROOVES, SAID STEM HAVING A NIB PROJECTING THEREFROM, AND A BULB EXTENDING BEYOND SAID END SURFACE OF SAID FRAME; A SPRING CLIP RECESS FORMED IN EACH SIDE SURFACE OF SAID FRAME ADJACENT SAID END SURFACE THEREOF; A SPRING CLIP AFFIXED TO SAID FRAME IN EACH OF SAID SPRING CLIP RECESSES AND EXTENDING BEYOND SAID END SURFACE AND SUBSTANTIALLY PARALLEL TO THE SIDE SURFACES OF SAID FRAME, EACH SPRING CLIP HAVING UNDULATIONS FORMED THEREIN IN THE PORTION THEREOF EXTENDING BEYOND SAID END SURFACE THEREOF; AN AIR DUCT MEMBER HAVING SUBSTANTIALLY PARALLEL TOP AND BOTTOM SURFACES, SIDE SURFACES SUBSTANTIALLY PERPENDICULAR TO THE TOP AND BOTTOM SURFACES OF SAID MEMBER, AN END SURFACE SUBSTANTIALLY PERPENDICULAR TO THE TOP AND BOTTOM SURFACES OF SAID MEMBER, AND AN OPEN END SPACED FROM AND OPPOSITE THE END SURFACE OF SAID MEMBER, EACH OF SAID SIDE SURFACES BEING OF SUBSTANTIALLY PLANAR CONFIGURATION AND EXTENDING BETWEEN SAID TOP SURFACE AND SAID BOTTOM SURFACE; A LONGITUDINAL DIVIDER EXTENDING SUBSTANTIALLY PERPENDICULAR TO THE TOP AND BOTTOM SURFACES OF SAID MEMBER SUBSTANTIALLY EQUIDISTANTLY FROM THE SIDE SURFACES OF SAID MEMBER, SAID LONGITUDINAL DIVIDER DIVIDING SAID MEMBER INTO TWO SUBSTANTIALLY EQUAL COMPARTMENTS; A PAIR OF SPACED APERTURES FORMED THROUGH THE END SURFACE OF SAID MEMBER, EACH OPENING INTO A CORRESPONDING ONE OF THE COMPARTMENTS OF SAID MEMBER; AN APERTURE FORMED THROUGH THE BOTTOM SURFACE OF SAID MEMBER AND OPENING INTO SUBSTANTIALLY THE ENTIRE AREA OF THE COMPARTMENTS OF SAID MEMBER; A LIP EXTENDING FROM THE SIDE SURFACES OF SAID MEMBER SUBSTANTIALLY COPLANARLY WITH THE BOTTOM SURFACE OF SAID MEMBER; AND A RIB FORMED IN AND EXTENDING FROM EACH OF THE SIDE SURFACES OF SAID MEMBER IN PROXIMITY WITH THE END SURFACE OF SAID MEMBER AND SUBSTANTIALLY PARALLEL TO SAID END SURFACE AND SUBSTANTIALLY PERPENDICULAR TO THE TOP AND BOTTOM SURFACES OF SAID MEMBER, SAID AIR DUCT MEMBER BEING ADAPTED TO BE POSITIONED ADJACENT SAID THEREMOMETER FRAME WITH THE END SURFACE OF SAID AIR DUCT MEMBER ABUTTING THE SAID END SURFACE OF SAID FRAME, WITH THE BULB OF THE WET BULB THERMOMETER POSITIONED IN ONE COMPARTMENT OF SAID AIR DUCT MEMBER AND THE BULB OF THE DRY BULB THERMOMETER POSITIONED IN THE OTHER COMPARTMENT OF SAID AIR DUCT MEMBER, AND WITH THE UNDULATED PORTION OF EACH OF SAID SPRING CLIPS CLAMPING A CORRESPONDING ONE OF THE RIBS OF SAID AIR DUCT MEMBER. 